The present invention relates to apparatus for processing handwriting inputs, e.g., an electronic tablet. More particularly, the invention relates to apparatus for processing handwriting inputs generated via cordless input pens.
Handwriting input processors are of various types known, among others, as electronic notebooks, keyboardless computers, drawing terminals, digitizing tablets, etc. Generally a planar input surface is provided (hereinafter referred to as a "tablet". The tablet includes some sort of matrix of electrode lines so that contacting of a pen tip to the surface of the tablet can be tracked via association with coordinates relating to every point of contact. By analyzing the coordinates associated with one or more points of contact, a handwritten input can be processed.
Heretofore, the point of contact between the pen tip and the tablet has been recognized via various methods. Among these methods are electromagnetic coupling, resistance change detection, and the like. With methods such as these, there is no need to additionally connect the input pen to a signal processing circuit and thus, the pen is not tethered. As a result, the user is free to pick up a pen and use it with high efficiency.
However, because the pen is not tethered, it can become lost. While in some cases alternate pens can be used, generally specially designed pens must be used. Thus, the loss of the pen can render the tablet useless unless another pen is obtained. Further, even if an alternate pen can be used, the difference in pen tips might be detrimental to the tablet surface thereby damaging the tablet.
Of course, to prevent loss of a pen it could be tethered to the tablet. However, tethering the pen limits its freedom and can lessen the efficiency of its use.